Rotary underreamer



April 24, 1928.

S. L. CAMPBELL ROTARY UNDERREAMBR Original Filed Feb. 1. 1926 2 Shasta-{3119a l INVEN TOR.

E/ewar/ Z. @mpkfl BY WM M 77444 A TTORNEYS.

April 24, 1928.

- s. L. CAMPBELL ROTARY UNDERREAMER W ZZ 2 Sheets-5mm 2 Original Filed Feb, 1926 I N V EN TOR 576W0f/ Z. ompd/ BY W ZM A TTORN E YS.

Patented Apr. 24, 1928.

UNITED STATES STEWART L. CAMPBELL. or

meme

ROTARY UNDERREAMER.

Application filed February 1, 1926, Serial No. 85,126. Renewed August 12; 1927.

'This invention relates to underreamers for use in enlarging holes such as oil well. holes, and especially for preceding the well casing whichris commonly placed in position and follows the boring tools.

reamers are well known in the art. The present invention.appertains more particularly to expansible underreamers having cutters which may be retracted for travel through the well casing and will automatiw cally open on exit therefrom.

It is desirable in such tools, that the cut ters be automatically retractible by an up ward pull against the bottom of the well lates to a tool of this character.

It is the primary object of this invention" to provide a tool of the character described which has a rugged body andin which provision is made for firmly interlocking the cutters with the body when in protracted p0- sition. Another object of this invention is to provide cutters which are movable longitudinally of and foldable against the body folded imposition; Fig. 3 is a section as seenon the line of Fig. 1; Fig. elis a section as seen on the line 44 of Fig. 2; Fig. 5 is a section as seen on" the line 55 of Fig. 2; Fig. 6 is an elevation partly in section showing another form of theninvention; Fig. =7 is a fragmentary view showing the invention embodied in a core barrel; Fig; 8 is an eleration-of a cutter with a portionof the stem.

broken away and a part of the cutting edge in section showing a renewable blade;- and Fig. 9 isv an end elevation partly in section of thestructiire shown inFig. 18. 1

Referring more particularly to, Figs. 1 to 5, the body ofthe underreamer is shown equipped at the upper end with a threaded tapered pin for connection with a stri'ngof drill pipe. The body. is formed of an outer shell 10 and a mandrel. The bore of the Such underexternally threaded at its lower end.

casing string, and the present invention re;

the pins. of the cutters.

shell is reduced in diameter at the upperend to receive a head 11 which is tapered and threaded at the outer end'to form the pinofa tool joint. The lower portion of the head is enlarged in diameter as indicated by 12 so as to form a shoulder which will,

BERKELEY, camronuiaassienoa fro JOHN GRANT, on y Los n ennas. CALIEQRNIA. r

abut the shoulder between the portion 01 the bore of the shell of reduced diameter and the portion of larger diameter. A hollow stem 13 depends from the head 11 and is tel-mediate the ends of the stem 13 is a cy A lindrical block 14; for pivotally supporting the cutters. r The mandrel fits slidably and snugly within theshell 10 so that it maybe removed therefromunless locked in position. At the lower end of the shell 10 areslots115 forming slip ways for cutters; The H lower end face .ofthe shell between slotsis inclined as indicated by 16. Extending through theblock 14L. are bores 17 to receive In order that the cutters may be properly aligned or registered with slots 15, the mandrelshouldbe lproperly located and fixed in position. To;

this end I have splined the mandrel shell by providing upon the mandrel tenons'18 at the head for-disposal in corresponding recesses in the shell. To look the mandrel and shell. together a pin or set screw extending through the shelland into the head may be employed, if desired.

Mounted in. the block .14: are the cutters. The cutters comprise wingportions 2O having cylindrical stems 21. The outer edges of the wings are bevelled as best shown in Figs; 3 and 4.. At the lower edges arerecesses 22 for receiving cutting blades 23.

which form the ultimate cutting elements of the type of cutters here shown. The cutter portions of elements 20 may heregarded as the pivoted carriers for the ultimate cutting ,1

elements. The recesses and cutting blades. are of such shape that the blades are held against moving downwardly outof the recesses. Pins 2-1 extend through the blades and through the wings to prevent lateral displacemcntof the blades. The blades present downwardly facing cutting edges or elements on the horizontally swinging cutters, cutting edges that cut downwardly into the formation. The upper outer corners of the wings are rounded as indicated by 25. The

cutters are mounted in the block by disposing the pins 21 in. holes 17. This provides for a pivotal mounting of the blades so that they maybe folded against the mandrel and also provides for a longitudinal movement. Mounted upon the pins 21 and above the block 14 are compression springs 26 engaging suitable abut-merits on the pins, such as set-screws 27. The springs tend to hold the cutters against the block 14. The upper ends of the slotslfi and the bottom faces of the block 14 are disposed substantially in registration so that when the wings 20 of the cuttors are registered with the slots 15, the springs 26, if unrestrained, will move and hold the cutters in their upper position with wings in slots 15 as shown in Fig. 1. The wings may be moved outwardly of the slot by pressing downwardly upon the upper sides thereof.

Suppose the underrea-mer is in expanded position and the cutters are below a well casing 28. If the underreamer is pulled upwardly, the cutterswill engage the casing 28 and be moved ('lownwardly out of the slots 15. Further upward movement of the cutters will act to swing them inwardly so as to fold them against the mandrel as shown in Figs, 2 and 4. This movement is a result of the contour of the bevelled and rounded corners 25 of the wings, and of the tangential or nonradial position of the cutters. On moving the underreamcr clownwardly, and out of the casing, the springs 26 Will pull the cutters upwardly, the latter in their initial movement into slots 15 riding againstthe inclined faces 16 of the shell and then into the slots, in which position they are securely locked in the body.

The lower end of the underreamer may be equipped with any suitable tool such as a fish tail bit 29. Circulation of slush from the drill pipe is provided for by the bore in the mandrel, and the water courses may be constructed in any suitable manner.

Referring to 6. a body is shown comprising a shell SO-of the same construction as just described. \Vithin the body is a mandrel 31 of similar construction to that before described and having a block 32 for cutters 33. The structure differs from that before described in having a lower block 34 provided with holes 35. These holes re ceive extensions 36 of the cutter pins, thereby providing for supporting the cutters upon both the upper and lower sides. The stems 36 are pivotally and slidably mounted in the head 34. A fish tail bit 37 is shown attached to thebottom of the mandrel. The ren'lainder of the structure is substantially that described in the form shown in Figs. 1 to 5 inclusive, and the operation of the device is substantially the same.

The underreamer may be adapted for use with a core barrel wherein samples of the formation are cut and captured. Such a structure is shown in Fig. 7 of the drawing. A core barrel shell or mandrel is indicated by 38, it having a shouldered portion 89 at the upper end. The shell 38 at the lower end is substantiallythe same shape as the shell of the underreamer body before described, slots being formed for the cutters. lVithin the shell is the mandrel comprising a core tube 40 with its lower edge 41 forming a crown cutter. A headlilis provided at the upper end and is tapered and threaded to provide for connection to a drill pipe string. Adjacent the lower end of the tube is a block 43 having longitudinally extend.-

ing holes to receive the stems 4A of cutters 45. The mounting of the cutters upon the block is substantially the same as that before describedso that the cutters may be expanded and contracted in the same manner. The core which is being cut enters the core tube moving upwardly and forcing any en trapped fluid through'the port in a valve seat 46 controlled by a check valve 4:7. Openings 48 in the tube above the valve provide for a. fluid passingfrom the bore of the tube outwardly to the space between the tube and the shell and then downwardly through courses as and around the lower portion of the tool.

In each of the forms shown. the cutters are moved downwardly out of slots in the body and then folded inwardly against a reduced portion of the body. This reduced portion may be a mandrel, a core tube or any other structure. .It is obvious that the collapsible cutter structure may be adapted to tools of various kinds.

One feature of the described structure, to which I wish particularly to call attention, resides in the method and manner of transmission of imposed stresses from the cutters to the body. By reference to Figure 3, wherein the cuttersarc shown in their expanded positions, it will be noted that the cutter blades 20 contact with the reduced portion 13 at points where the surfaces oi"? contact are'not parallel with the lines of 'adial thrust through the cutters, but that such surfaces of contact make a sul'istantial angle'to the lines of radial thrust through the cutters. The outer edge of the cutter is subjected not only to a circumferential thrust due to the cutting action of the tool but is also subjected to a radial thrust duo both to the cutting action and what may be termed the squeezing action of the strata as the tool is forced down by the weight above it. Consequently in order to save the pivot stems from these great forces it is necessary that the cutters hear back against.- the body in such a manner as not only to transmit the circumferential thrusts directly to the body, but also as to transmit the radial thrusts directly to the body. The bearing of each cutter againstthe back side of the ill) laterally so as to be ret notch 15 of course directly transmits circumferential thrusts to the body; but the cutters cannot be too tightly fitted in the notches and coi'isequently the circumferential thrusts will tend at least to some degree to twist or rotate the cutters in the notches as if the notches formed fulcrums in which the cutters swing. The notches, however, do not support the cutters to any substantial extent-against the imposed radial thrust, and that thrust is taken directly by the body at the said surface of contact between the body and each cutter, which surface of contact will be seen from Figure 3 to make a substantial angle with the line of radial thrust through the cutter. At the same time the angle made by this surface of contact is also preferably such, being oblique to the radial line of the cutter through its own swinging axis, as also to transmit directly to the body the circumferential thrust. In order to make these considerations clear in Figure 3Ithe radial line through one cutter is indicated by the dotted line B which line also indicates substantially the radial line of thrust. The surface of contact for that cutter is indicated by the dotted line denoted S. The direction of force application from the cutter to the reduced portion 13 of the body is indicated by the dotted line are row denoted F, and the application of cir cumferential force to the cutter is indicated at C. From a consideration of these several forces it will be understood now that the bearing of the cutter on the body, at its, stress transmittingpoint F at the described surface of contact, so as to transmit the force in the direction indicated at F, allows the resultant of the force R and of the force caused by G to be transmitted directly to the body withoutimposing commensurate strains upon the pivot stem.

lVhat I claim is:

1. A tool of the character described comprising the combination of a body provided with a cutter receiving space, cutters mounted thereon for longitudinal movement and lateral swinging movement about longitudinal axes'whereby they may be swung 'acted or so as to be, protracted, SZLIdlJOClV having ways for said cutters whereby the latter are held protracted in a selected longitudinal position, and spring means tending to move said cutters longitudinally into protracted position.

2. A tool of the character described com prising the combination of a body provided with a cutter receiving space, cutters mounted on said body for longitudinal movement and lateral swinging movement about longitudinal axes whereby to be protracted or retracted, said body having cutter receiving notches at one end of said space to interlock said cutterswith said body in protracted position of said cutters, said cutters when located in said space being free to be swung laterally so as to be folded into retracted position, said body having cam faces leading to said notches engaging with said cutters tending to swing the latter into protracted position upon initial longitudinal movelaterally so as to be folded intoretracted,

posit-ion, spring means tending to move said cutters longitudinally into said notches, said body having inclined faces between said notches cooperating witl'rsaid cutters tending to swing the latter into protracted position upon initial movement ofsaid cuts tors into said notches.

4:. A tool of thecharacter described com-,

prising the combination of a mandrel having a peripheral enlargement forming a block provided with longitudinally extend ing holes, cutters having pivot stems mounted in said holes so as to slide longitudinally and to, swing laterally aboutlongitudinal axes, a shell disposed over said mandreland fixed thereto, said shell ending short of the lower end of said mandrel to provide a space in which said cutters may be swung freely laterally into retracted or protracted position, said shell having notches at its lower end to receive said cutters and hold the latter in protracted position, the end of said shell between said notchesbeing arranged with inclined faces for cooperation with said cutters so as totend to swing the latter into protracted position on initial cngagement therewith, A and compression springs mounted on said stems engaging the upper side of said block and tending to movesaid cutters longitudinally into said notches. r

5. A tool of the character described comprising the combination of a mandrel having a peripheral enlargement forming a block provided with longitudinally extending holes, cutters having pivot stems mounted in said holes so as to slide longitudinally and to swing late ally about longitudinal axes, a shell disposed over said mandrel and fixed thereto, said cutters being arranged to be moved below said shell so as to be swung freely into retracted or protracted position, said shell having notches at its lower end to receive said cutters and hold the latter in protracted position, the end of saidshell between said notches being arranged with inclined faces for cooperation with said cutters so as to tend to swing the latter into protracted position, and means tending to move said cutters longitudinally into said notches.

6. A tool of the character described comprising the combination of a mandrel, cutters having pivot stems mounted on said mandrel so as to slide longitudinally and to swing laterally about longitudinal axes, a shell disposed over said mandrel and ending short of the lower end to provide a space in which said cutters may be swung freely laterally into retracted or protracted position,'said shell having notches at its lower end to receive said cutters and hold the latter in protracted position, the end of said shellv between said notches being arranged with inclined faces for cooperation with said cutters so as to tend to swing the latter into protracted position, and springs mounted on said stems tending to move said cutters longitudinally into said notches.

7 A toolof the character described comprising the combination of a mandrel, curters having pivot stems mounted on said mandrel. so as to slide longitudinally and to swing laterally about longitudinal axes, a shell disposed over said mandrel, said cutters being arranged to be moved below said shell so as to be swung freely laterally into retracted or protracted position, said shell having notches at its lower end to receive said cutters and hold the latter in protracted position, the end of said shell between said notches being arranged with inclined tacos for cooperation with said cutters so as to tend to swing the latter into protracted position, and means tending to move said cutters longitudinally into said notches.

8. A tool of the character described, comprising a body, a cutter mounted to swing laterally about a vertical axis and to slide vertically in the body, said axis being eccentric with relation to the vertical central axis of the body, the cutter extending laterally from said axis and adapted to swing to and from a position where its outer lateral edge projects beyond the body, a cutter receiving notch into which the cutter enters by ver tical movement when it is in a position nonradial with relation to the l: ody, and the up per outer corner of the cutter being bevelled for engagement by a casing for swinging the cutter.

9. A tool of the character described, comprising a body, a cutter element mounted in V the body to move longitudinally and swing laterally about a longitudinal axis. meansacting directly between the cutter element and the body to cause lateral swinging of the cutter element in one direction by virtue of longitudinal movement in one direction, and a spring tending to move the cut ter element longitudinally 11'] said direction.

10. A tool of the character described, comprisinga body, a cutter element mounted in the body to move longitudinally and swing laterally about a longitudinal axis, a spring tending to move the cutter element longitin dinally in one direction, and the body having a notch into which the cutter clei'uei'it enters by its spring impclcd longitudinal movement when in a certain lateral position.

11. A tool of the character described, comprising a body, a cutter element mounted in the body to move longitudinally and swing laterally about a longitudinal axis. means acting between thecutter and the body to cause a lateral swinging of the cutter ele ment by virtue of a longitudinz-il movement in one direction, thebody having a notch into which the cutter element enters by longitudinal movement when in a certain lateral position, and a spring tending to move the cutter element longitudinally in said direction.

12. A tool of the character described, comprising a body, a cutter element mounted in the body to move longitudinally and swing laterally about a longitudinal axis, means to lock the cutter element against lateral swinging movement, said means being rendered operative by virtue oi longitudinal movement in one direction or" the cutter element in a certain lateral position, and a spring tending to move the cutter element longitudinally in said direction.

13. A tool of the character described, comprising a. body, a cutter element mounted in the body to move in a longitudinal direction and to swing in a lateral direction on a longitudinal axis, the longitudinal swinging axis of the cutter element being eccentric with relationto the longitudinal central axis of the body, the cutter element extending laterally from said axis and adapted to swing to and from a position where its outer lateral edge projects beyond the body, means acting between-the cutter element and the body to cause its motion toward projecting position by virtue of longitudinal movement in one direction, means limiting the swinging movement of the cutter element to positions non-radial with relation to the body, the upper outer corner of the cutter element being beveled "for engagement with the lower end of a casing, and a spring tending to move the cutter element longitudinally in said stated direction.

let. A tool of the character described, comprising the combination of a body. cutters mounted on said body for longitudinal move ment and lateral swinging movement about a longitudinal axis whcrebv they ma be swung laterally so as to be retracted or protracted, said body having inclined cam faces against which the cutter-s move longitudinally and which tend to swing the cutters to protracted position by virtue of their longitudinal movement in one direction, and

' means to move the cutters longitudinally in said direction. a i

15. A tool of the character described, enibodying a body having aplurality o'l' longitudinal holes grouped about the body axis, cutter carrying pivot stems in the holes, cutter elements mounted onthe pivot stems to swing on their longitudinal axes to and from protracted positions, and spring actuated means for causing swinging movement of the cutter elements toward protracted positions, includingsprings mounted in the body and acting on the pivot stems within the body.

16. A tool of the character described, enibodying a body having a plurality of longitudinal holes grouped about the body axis, cutter carrying pivot stems in the holes, cutter elements mounted on the pivot stems to swing on their longitudinal axes to and from protracted positions, and spring actuated means for causing swinging movement of the cutter elements toward pro tracted positions, including springs mounted around the pivot stem-s in the body, means limiting the swinging of the cutter elements to positions non-radial with respect to the body axis, and the upper part of the cutter element being bevelled for engagement by a casing to swing the cutters away from their protracted positions.

17. A tool of the character described, embodying a body having a plurality of longitudinal holes grouped about the body axis, cutter carrying pivot stems in the holes, cut ter elements mounted on the pivot stems to swing on their longitudinal axes to and from protracted positions, spring actuated means for causing swinging movement of the cutter elements toward protracted positions, including springs mounted around the pivot stems in the body, and the body having a water course leading into the longitudinal holes to wash the pivot stems and springs.

18. In a tool of the character described, a body comprising an internal mandrel and a removable shell surrounding the mandrel, the mandrel having a longitudinal cutter stem bore ending in a spring receiving recess which opens out to the exterior surface of the mandrel and is normally covered by the shell, a cutter stem in the bore and extending into the recess, a spring on the cutter stem in the recess, and a cutter element carried by and swinging about the axis of the cutter stem.

19. A tool of the character described, comprising a body having an inward offset with a reduced portion below the offset, the part of the body above the inward olfset forming an upper head, vertical pivot stems mounted in the head on axes eccentric to the central axis of the body, cutter carriers mounted on the lower ends of the stems and adapted to prising a body having an inward oflset, the

part of the body above'the inward oflset forming an upper head, a vertical pivot stem inithe upper head eccentric of the central axisot' the body, and a cutter carrier pro-' jecting below said upper head and mounted on and supported by said pivot stem exclu sively and to swing horizontally, and means, including a coiled spring surrounding the pivot stem within the body, acting to support the stem and to rotate it to swing the cutter carrier. 21. A tool of the character described, com prising a body having a relatively large portion and'having a relatively horizontal recessed portion extending below the said large portion, cutter carrying pivot pins mounted vertically in the large portion, cutter ele ments depending from the pivot pins and extending below the large portion around the recessed portion, said cutter elements swinging about the vertical axis of theirrcspective pivot pins, and each cutter element contacting with the recessed portion at the back of the cutter receiving recess on a surface of contact making a substantial angle with the line of radial thrust through the cutter element for support against both circumferential and radial imposed stresses.

22. A tool of the character described, C01l1- prising a body having an inward offset, the part of the body above the inward offset forming an upper head, a vertical pivot stem in the upper head eccentric of the central axis of the body, and a cutter carrier depending from the lower end of the eccentric pivot stem projecting below the upper head, and pivoted to swing around the axis of the pivot stem, a reduced portion of the body below the inward ofi'set being arranged inwardly of the pivot stem, the inner end of thevpivoted cutter carrier bearing against the reduced portion on a surface of contact making a substantial angle with the line of radial thrust through the cutter carrier to transmit both radial and circumferential thrust directly from the carrier to that portion of the body.

23. A tool of the character described, comprising a body having an inward olfset forming a cutter receiving recess, the part of the body above the inward offset forming an upper head, a vertical pivot stem in the upper head eccentric ot' the central axis of the body, a cutter element mounted on the lower end of the pivot stem in the recess to swing horizontally about the axis of the stem between contracted and expanded positions, means limiting the swinging of the cutter element to positions non-radia1 with respect to the body axis, the upper outer part of the cutter element being bevelled for em portion at the back of the cutter receiving recess inward of the pivot stem on a surface of contact making a substantial angle with the line of radial thrust through the cutter element, for support on the body at a point inward of the pivot axis, against both radial and circumferential imposed stresses; at least one of the two said contacting faces being non-concentric with the pivotpin so as to present no extended rubbing surfaces at the point of contact.

In witness that I claim the foregoing I have hereunto subscribed my name this twenty fifth day of January, 1926.

STEl VART L. CAMPBELL. 

